Methods of anchoring dentures over crown copings and post abutments

ABSTRACT

A known elastomeric non-methyl methacrylate soft material has been used as a soft denture liner material. The material includes powder and liquid components which are mixed together and cured. The invention involves lining an underlying surface of an acrylic overdenture, wherein the overdenture is applied over a crown coping over a tooth or over a post with a ball or hour-glass shaped abutment. A liner is formed having the characteristics of being flexible, resilient, shape retentive, hydrophobic, soft, spongy and cushiony. A known sealer component is then applied over the liner to create a non-absorbent exterior surface seal and glaze. By varying the powder to liquid ratio, the material can be made more dense thus hardening or softening it for various applications. By removing the exterior surface and roughening the material, it can easily be adjusted, repaired or refurbished. The material allows for a quick cure or a dental laboratory processed cure and is compatible for either chairside or laboratory use.

RELATED APPLICATIONS

The present application is a continuation-in-part of application Ser.No. 08/408,597, filed Mar. 22, 1995, now U.S. Pat. No. 5,678,993, whichis a continuation-in-part of application Ser. No. 08/233,849, filed Apr.26, 1994, now U.S. Pat. No. 5,513,988, issued May 7, 1996.

TECHNICAL FIELD

The present invention generally relates to clinical uses of soft dentureliner materials and in particular to new and novel clinical uses of aknown elastomeric non-methyl methacrylate soft denture liner material.

BACKGROUND OF INVENTION

For decades, restorative dentists and dental product manufacturers haveattempted to develop a soft liner for dentures and prosthetic devicesaddressing the various short term and long term clinical challengespresented by partially and fully edentulous patients. Examples of longterm uses of soft denture liners may be indicated where the patient hasundercuts caused by severe alveolar ridge resorption; anatomical voidsrequiring obturators; anatomical growths such as palatal tori; and,knife edge alveolar ridges. Examples of short term uses of soft dentureliners include overdentures supported by implants or teeth;post-surgical prosthodontic situations that require interim lining whileboth soft and hard tissue heal; and, gasket like connectors and linersover and around existing teeth.

Various types of soft denture liners exist in the art which are intendedfor short term or long term service. Soft denture liners are known inthe art which are laboratory-processed and intended as long term liners,such as include Molloplast-B™ (Buffalo (Dental). Also known in the artare chairside-processed soft liners intended for short term service.These include Lynal™ (L.D. Caulk/Dentsply) and Visco-Gel™(Ash/Dentsply). Until the methods of the present invention weredeveloped, no soft denture liner was known that was chairside orlaboratory-processed and intended for short, intermediate and long termclinical use.

In addition, prior art liners have different problems associated withtheir clinical applications. In particular, silicon soft liner materialsmust be "glued" onto the hard acrylic surface with an adhesive bondingagent, and often this bonding agent contains a methyl methacrylatemonomer. These self-curing adhesives leach into the soft material andharden it.

Moreover, adhesives harden and crack at the "seam," or junction wherethe soft material is glued on to the hard acrylic. Lactic acid, alcohol,and/or medication accelerate this separation. At this point, bacteria,fungus, odor, debris, and stain penetrate the soft liners. This naturalabsorption degrades the soft liners creating a hardening, peeling, aswell as chemically and physiologically unstable condition.

In addition, the repair process of other existing materials is difficultsince the base material either flakes off when trimmed, or it cannot bere-molded with standard dental tools. Also, to "glue" small sections ofliner onto thin acrylic edges is difficult or impossible as the linersbreak off under the constant pressure which occurs in the oral cavity.

There are various products which use heat or light to cure resins ofvarious formulation onto prosthetic devices. Almost all of theseformulations require a bonding agent which runs into the same problemsas mentioned above. Many of these finished liners absorb liquidsaccelerating their deterioration.

Another category of liners which are temporary in nature are known as"tissue conditioners". These gels or stick-on resins last only weeks ora few months before they peel-off. They usually are soft due to highporosity, and thus they absorb liquids which ultimately breakdown thematerials. The absorbency allows bacteria and odor buildup in the mouthcreating an undesirable situation.

Hence, prior to the development of the present invention, a need existedfor clinical techniques using a non-methyl methacrylate soft linermaterial capable of remaining soft during intermediate to long termservice and is chairside or laboratory compatible.

SUMMARY OF THE INVENTION

The clinical methods and techniques of the present invention use a knownelastomeric material which overcomes many of the disadvantages of priorart liner materials. This material is a non-methyl methacrylate softmaterial which effectively fuses to acrylic surfaces or to itselfwithout a gluing agent. The present invention is based upon therecognition that the known elastomeric non-methyl methacrylate softmaterial described above could be used in permanent lining techniquesheretofore not practiced in the prior art. Thus, while the prior artused such material as a reline material for dentures it was notpreviously recognized that the attributes of that material made itparticularly useful for other dental techniques. It was also notpreviously recognized that the curing characteristics inherent in thematerial made it possible to apply the material at chairside to cure,for example, in only five minutes in the patient's mouth, although otherconventional methods of curing may be used. The characteristics of theelastomeric non-methyl methacry-late material make it particularlysuitable for diverse applications as a long lasting, soft, hydrophobic,cushion-like material chemically bonded onto any acrylic surface.

The known liner material used in the clinical techniques of the presentinvention is formed by blending a powder component ofpolyethylmethacrylate and a liquid component of Di-n-butyl phthalate,ethyl acetate and ethyl alcohol which are mixed together until all ofthe powder particles are totally moistened. It has been discovered andis an element of the present invention that softness of the material canbe varied for each clinical use and may be varied for each patient aswell. The softness or hardness of the material is dependent upon varyingthe powder to liquid ratio. The ratio of powder to liquid may varywithin the range of 2:1 for softer material to 3:1 for harder or densermaterial. The resultant mixture is then applied onto dentures by beingspatulated on the denture surface or is formed in various shapes andconfigurations depending upon the given clinical application. Apolyvinyl chloride/polyvinyl acetate copolymer dissolved in a methylethyl ketone solvent forms a sealer component which is then applied overthe liner to create a nonabsorbent, moisture impervious surface seal andglaze.

The objects of this invention are clinical techniques and applicationsfor intermediate and long term service of the above noted non-methylmethacrylate material. These techniques generally include using thematerial to form (1) linings of gaskets over an anchor device protrudingfrom tissues such as implant attachments or posts, implanted into theroot of a tooth; (2) gaskets over ball abutments and hader bars; and,(3) linings of gaskets around an anchor device protruding from tissuesuch as a crown coping over an existing teeth.

Other advantages and aspects of the invention will become apparent uponmaking reference to the specifications, claims, and drawings to follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a kit for packaging the materials usedin the methods of this invention;

FIG. 2 is a plan view of a denture having the liner of the materialsapplied thereto;

FIGS. 3-5 are cross-sectional views taken through FIG. 2 along the lines3--3, 4--4 and 5--5, respectively;

FIG. 6 is a bottom plan view of the material over the tissue and healingcaps;

FIG. 7 is a perspective of a removable partial denture having a distalextension formed by the materials of the present invention;

FIG. 8 is a plan view of a denture having pass-through opening to form agasket around existing teeth in which the gasket edge is lined accordingto the present invention;

FIG. 9 is an exploded view of a denture having sockets lined using amethod of the present invention to receive ball abutments and a crowncoping over a tooth;

FIG. 10 is an upper denture wherein an obturator to fill an anatomicalvoid is formed using a method of the present invention;

FIG. 11 is a side view of a post with a ball abutment;

FIG. 12 is a side view of a post embedded in the root of a tooth; and,

FIG. 13 is a side view of a post embedded in the root of a tooth wherethe ball abutment is aligned for emplacement in a denture.

DETAILED DESCRIPTION

While this invention has the capability of being employed in manydifferent forms, there is shown in the drawings and will herein bedescribed in detail a preferred embodiment of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the broad aspect of the invention to the illustrated usages.

The characteristics of the elastomeric non-methyl methacrylate dentureliner material used in the clinical techniques of the present inventionmake it particularly suitable for diverse applications as a longlasting, soft, hydrophobic, cushion-like material which chemically bondsonto any acrylic surface without need of a gluing agent. The materialmay be processed at chairside or in the laboratory using a hot watercure. The material fuses to acrylic by cross linking into the exteriorpores thus establishing a chemical and mechanical bond. The materialremains spongy soft, flexible, shape retentive, and permanently attachedto the underlying hard material.

The liner material used in the present invention is formed by blending apowder component comprised of a polyethylmethacrylate, and a liquidcomponent comprised of a mixture of Di-n-butyl phthalate, ethyl acetateand ethyl alcohol. The liquid component and the powder component areslowly mixed together until all of the powder particles are totallymoistened. Essential to the methods of the present invention is thedegree of softness of the material for a given clinical use. Thesoftness or hardness of the material is dependent upon varying thepowder to liquid ratio. For example, where more powder is used a moredense material results which in turn is harder. Variations of powder toliquid may be within the range from 2:1 for softer material to 3:1 ormore for harder material.

The various components of the material can conveniently be prepackagedin a kit. FIG. 1, for example, illustrates such a kit 10 which couldtake any suitable form, for example, a carton in which the componentswould be packaged. Thus, as shown therein a bottle or container 12 couldbe used for a powder component while a liquid component could bepackaged in a bottle 14. A sealer would be packaged in bottle orcontainer 16. In the practice of most of the methods of the presentinvention, three parts of loosely packed powder from container 12 ismixed into one part of liquid from container or bottle 14 slowlystirring until all powder particles are thoroughly saturated.

Powder component in container 12 would be polyethylmethacrylate whilethe liquid component in bottle 14 would be Di-n-butyl phthalate, ethylacetate and ethyl alcohol solution. The sealer in container 16 would bea polyvinyl chloridepolyvinyl acetate copolymer dissolved in a methylethyl ketone solvent component which would be capable of providing anone absorbent surface seal and glaze when applied over the mixture ofthe cured powder and liquid component.

Sealer 26 as disclosed in the drawings can air dry in two minutesestablishing a hydrophobic, non-absorbent, high-gloss, stain resistant,surface finish. This step is repeated for a stronger external bond. Noother soft line product uses such a sealer.

The finished soft lined surface will remain soft for multiple years,even in the oral cavity. The use of the sealer 26 effectively preventslactic acids, bacteria, fungus and other substances from penetrating thehydrophobic soft liner. Thus, internal degradation does not occur as thesealer 26 keeps out all oral fluids.

Since no methyl methacrylate or bonding agent is used in this procedure,the leeching of methyl methacrylate into the soft material does notoccur keeping the liner softer for a longer period of time. The specificmethod of mixing, application, and curing in hot water (under 25 PSI ofpressure if desired) accelerates the set of the soft material. Thetolerance of temperature extends from 125° F. up to 165° F. so as not towarp the acrylic denture, and the pressure can vary from 15 PSI to 40PSI for the same results.

Clinical uses of the liner material employed in the methods of thepresent invention is best disclosed with reference to the followingexamples.

EXAMPLE I LINING OF FULL DENTURES AND LINING DENTURE PASS-THROUGH GASKETHOLES SURROUNDING EXISTING TEETH OR ANCHOR DEVICES

The methods of the present invention may be used to form a lining on theunderside of full dentures to improve denture wear, cushion and fit. Inaddition, as disclosed in FIGS. 2, 5 and 8 a method has also beendeveloped to use the liner material disclosed herein for gasketanchoring. This could be done for retention of a denture as a gasketaround the circumference of a pass-through hole. The material can be asa gasket retentive liner 28 bonded the circumference of a hole 30 (suchas in FIGS. 2 and 5) and onto the acrylic surfaces to anchor the dentureto patient's existing teeth. FIGS. 2 and 5 disclose using the liner forretention of a denture as a gasket 28 around the circumference of a passthrough hole 30 for existing teeth. The hole 30 is enlarged to thedesired size. Then the material is blended over, under and around thegasket hole 30, and onto surrounding acrylic surfaces 22. The followingchairside technique is preferably used to apply the lining materialeither as a full denture reline or in lining gasket pass-through holes:

1. Relieve undercuts, grind (1-2+)mm of space to receive materialhollowing out entire tissue side of denture to allow room, especiallywhere gum ridge peaks; Roughen peripheral roll & (3+)mm onto outersurface of denture; Clean & dry denture where reline applied;

2. Pour powder, (all at once), into a plastic mixing cup of liquid in avolume ratio of 3 parts powder into 1 part liquid; Gently mix until allthe powder particles are moistened; The mixture consistency instantlyturns "sticky" or "honey-like"; (Slightly more liquid thins the mix,increases working time, and makes a slightly softer reline);

3. Immediately, generously spatulate and spread the sticky mixture ofmaterial evenly onto totally dry denture surface;

4. Patient moistens lips with tongue as this material will not adhere toany saliva or wet covered areas; Insert the denture filled with materialinto patient's mouth; Have the patient close gently into occlusion for 1to 11/2 minutes;

5. Remove denture from the mouth; Blend and taper excess material withfinger coated with material liquid to completely overlap the peripheralroll (3+)mm onto acrylic surface. (Immediately cure);

6. Place denture in cup with relined side up, add steaming hot water(from 125° F. to 165 degrees F.) for (10) minutes;

7. Chill finished relined denture in cold water to temporarily hardensoft liner; Remove excess flash with finishing stone or acrylic burtapering reline on the labial and buckle surface; Finish with a largerubber point, and wet rag wheel & pumice, if desired; High gloss notnecessary;

8. Apply a complete coat of sealer with brush or cotton tip applicatorover the totally dry material soft liner; Material forms anon-absorbent, high gloss, stain resistance exterior surface; Sealer airdries in (2+) minutes--then, repeat with a second complete coating andallow to dry. A third coating on non-retention area is acceptable.

An advantageous property of the material are its curing characteristics.For example, as previously noted the material can be cured in 10 minutesin steaming hot water, at chairside or in a jig. Alternatively, thematerial could be cured in 45 minutes in a flask or in only 5 minutes inthe mouth for small, thin area relines.

EXAMPLE II LINING OVERDENTURES FOR IMPLANT HEALING CAPS, BALL ABUTMENTS,CROWN COPING OVER TEETH AND HADER BARS

FIG. 11 discloses a post 50 with a ball abutment 36. The post 50 isscrewed into the root 52 of a tooth 54, as shown in FIG. 12. FIG. 13illustrates the alignment of the ball abutment 36 in the overdenture 34while the post 50 is embedded in the root 52 of a tooth 54.

FIG. 6 discloses the reline material used in overdentures for implanthealing caps 34 and, as disclosed in FIG. 9, in lining overdentures toreceive a crown coping over a tooth 37, ball abutments 36 or otheranchor devices protruding from the tissue surface. FIG. 6 discloses fivehealing caps 34. The coating of the cured material with the sealerprovides a non-absorbent exterior surface so as to maintain overdenturesoftness, and prevent discoloration, odor and bacteria ingress. No otherpolyethylmethacrylate resin uses this technique at the dentist'schairside or in the operatory or in the dental laboratory.

Where the material of the present invention is used immediately afterinitial surgery to install implants as an implant overdenture softliner, the load of powder to liquid is varied to form a softer material,usually in the range of 2 to 1. When the material is used to stimulateand cushion healing caps during transitional healing stages aftersurgery, the load of powder to liquid is varied to form a slightlyharder material, usually in the range of 2.5 to 1. When the material isused to enhance anchoring over a crown coping over a tooth or ballabutments, as disclosed in FIG. 9, then a proportion of 3 to 1 ispreferred. In either clinical use the following steps would bepracticed:

1. Trim back and relieve the tissue side of temporary denture with anyacrylic bur to allow for unobstructed seating initially over the tissuearea, and again reline over the healing cap(s) when exposed;

2. Pour material powder, (all at once) into liquid in a volume ratio of2 to 3 parts powder into 1 part liquid; Gently mix until all the powderparticles are moistened; Consistency instantly turns "sticky" or"honey-like"; (Slightly more liquid thins the mix, increases workingtime, and makes a slightly softer reline);

3. Immediately, spatulate the sticky mixture of material into the drytissue side of the denture previously reamed-out in Step (1); For largesurface relines follow step 4a; For small surface relines and forrelines over healing cap(s), when exposed, follow step 4b;

4a. Seat over tissue area; patient gently closes into centric occlusionfor (1) minute; remove denture; taper and blend excess material withfinger coated with material liquid to overlap the peripheral roll (3+)mmonto outer acrylic surface; Immediately, process in steaming hot water,(up from 125° F. to 165 degrees F.) for (10) minutes;

4b. Seat over tissue area, and over healing cap(s), when exposed; Havepatient close gently into centric occlusion for in-the-mouth cure in (5)minutes for thin, small area relines; Can also cure in steaming hotwater in (10) minutes for larger volume relines.

5. Post curing, chill finished reline in cold water to temporarilyharden soft liner. Trim excess material using finishing stone, acrylicbur and large rubber point. Finish with a wet rag wheel & pumice for asmooth surface;

6. Apply two complete coats of Sealer over totally dry reline to form anon-absorbent, high-gloss surface, Sealer air dries in (2+) min., andrepeat with a second coat to repel fluids, bacteria, odor and stain. Athird coating over non-retentive areas is acceptable.

7. For rebonding, adjustments, and refittings the previously notedchairside techniques would then be used.

The above procedure creates a soft liner on the tissue side of a dentureduring the transitional healing period after installation of an implant.Due to the softness of the material it creates a light functional loadsystem for moderate vertical stress during osseointegration of theimplant cylinder into the jaw bone. Increasing the powder ratio makesmaterial denser or harder, thus allowing for incremental loading. Thehardest concentration of powder allows for extended use as a gasket toanchor prosthetic devices onto various fixed implant attachments.

EXAMPLE III LINING OVERDENTURES FOLLOWING SURGICAL PLACEMENT OF IMPLANTS

Due to the ability to vary the liner's degree of softness, the materialis well suited to aid in the progressive healing process following thesurgical placement of implants. Specifically, one or two weeks followingthe implant placement, the tissue side of the overdenture is lined for asoft, light load. A powder to liquid load of approximately 2 to 1 ispreferred. After suture removal, the suture line or indentation isblocked with dry foil or suitable material and relined following thetechnique disclosed in Example I above. The soft material must notinterfere with the healing site or the newly-formed flap. The soft linercushions tender areas and provides a hygienic, non-absorbent surface.

After an appropriate implant integration phase, a second application ofsoft liner is applied to the tissue side to cushion and anchor onto thehealing caps. A powder to liquid load of approximately 2.5 to 1 ispreferred. This healing cap overdenture enables a gradual healing loadwith light functional stimulus to the implant. This thin area relinewill cure in the mouth in approximately five (5) minutes.

After attachment of the ball abutments or the bar connectors, theoverdenture is relined to form a gasket over the balls or bars withoutO-rings or clips. A powder to liquid load of approximately 3 to 1 ispreferred. This soft liner will absorb torque pressures and provideretention for long term service with easy adjustment.

EXAMPLE IV FORMING OVERLINERS FOR ANATOMICAL GROWTHS AND DENTURE INSERTSFOR ANATOMICAL VOID

Given that the material used in the methods of the present inventionbonds onto itself, clinical techniques have been developed to formoverliners for anatomical growths as well as forming obturators andother inserts for anatomical voids. FIGS. 2 and 4 disclose use of thematerial for extension over large voids 32 on denture surfaces for usein palatal tori. Though the recommended peripheral roll formed from thematerial should have a height of between 1.5 to 3 mm, the material canbe molded to one inch or more to form an obturator 38 for patients withcleft palates as disclosed in FIG. 10. When covering anatomical growthsor filling anatomical voids, a load of approximately 2.5 to 1 to form asofter finished product is preferred.

EXAMPLE V GASKETS OVER EXISTING TEETH

A softer load as described in Example IV may be used to attach acrylicstents onto existing teeth to prevent teeth grinding. This material canalso be used to gasket onto existing teeth inside of a mouth guard forretention and cushioning or inside of a stent as part of a medicationdelivery system. For example, a stent formed to extend below thegingival margin may retain and dispense topical medication along thegingival tissue. The material is capable of this clinical applicationbecause of its capacity to gasket onto teeth while containing themedication for time release dispensing.

EXAMPLE VI FORMING DISTAL EXTENSION FOR REMOVABLE PARTIAL DENTURES

As disclosed in FIG. 7 the material can be used to stabilize a partialdenture by molding a flange or saddle area 40 to the residual ridge 42.The material allows saddle area 40 to grip undercuts, contours to muscleform and alveolar ridges to help anchor partial dentures. The prior artuses hard acrylics for the saddle having a lower peripheral edge whichis both sharp and uncomfortable. In contrast, the soft extensions of thepresent invention allow the saddle areas 40 to flex during dentureinsertion or removal. Once in place, the saddle areas 40 return to theiroriginal position. In addition, as bone absorption flattens existingridge configurations, this material cushions, anchors, and stabilizesdentures onto the changing ridge structure. Thus, the material takesfull advantage of the underlying undercuts while providing the comfortof a soft cushion base.

For a removable partial denture to accommodate the soft liner materialused in the methods of the present invention, approximately 2-3millimeters of relief is necessary under the denture saddle to allow fora minimum of 1 millimeter of hard acrylic and 1-2 millimeters of softliner material. Preferably a proportion of 2.5 parts powder component to1 part liquid component is used.

After blending the powder component and the liquid component, theresultant material is formed over the peripheral roll of the dentureonto the surrounding acrylic surface, for more surface contact and thusa better and more permanent chemical bond. The lack of a seam at thejunction where the soft reline is bonded onto the hard acrylic preventsseparation of the soft material from the hard acrylic.

EXAMPLE VII MAINTENANCE OF DENTURES

The soft liner material used in the present invention can be trimmedusing standard dental tools; and, it rebonds to itself for fast, simplerepairs at chairside or in a dental laboratory. Re-sealing of theexterior surface should be initiated once per year which extends thelongevity of service from intermediate to long term. To reseal, (1) theexisting surface sealer is ground off, (2) the surface is smoothed, (3)the surface is dried, and (4) two new coats of sealer are painted on.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the broader aspects of theinvention. Also, it is intended that broad claims not specifying detailsof a particular embodiment disclosed herein as the best modecontemplated for carrying out the invention should not be limited tosuch details.

We claim:
 1. A method of lining an underlying surface of an acrylicoverdenture, wherein the overdenture is applied over a crown coping overa tooth, the method using a non-methyl methacrylate soft liner material,the material including a powder component of polyethylmethacrylate and aliquid component being an admixture of Di-n-butyl phthalate, ethylacetate and ethyl alcohol, the method comprising the steps of:blending 3parts powder component into 1 part liquid component; forming anelastomeric material by mixing the powder component into the liquidcomponent until all of the powder component is thoroughly moistened;and, applying the elastomeric material to the underlying surface of theoverdenture.
 2. The method of claim 1 further including the stepof:applying a sealer over the exterior surface of the liner to create anon-absorbent exterior surface seal and glaze.
 3. The method of claim 2wherein the sealer includes a polyvinyl chloride/polyvinyl acetatecopolymer dissolved in a methyl ethyl ketone solvent.
 4. A method oflining an underlying surface of an acrylic overdenture, wherein theoverdenture is applied over a post with a ball abutment, the methodusing a non-methyl methacrylate soft liner material, the materialincluding a powder component of polyethylmethacrylate and a liquidcomponent being an admixture of Di-n-butyl phthalate, ethyl acetate andethyl alcohol, the method comprising the steps of:forming a firstelastomeric material by mixing approximately 3 parts powder componentinto approximately 1 part liquid component until all of the powdercomponent is thoroughly moistened; and applying the first elastomericmaterial to the underlying surface of the overdenture.
 5. The method ofclaim 4 wherein the overdenture is applied over the post approximately 1to 2 weeks following placement of the post.
 6. The method of claim 4further including the step of:applying a sealer over the exteriorsurface of the liner to create a non-absorbent exterior surface seal andglaze.
 7. The method of claim 6 wherein the sealer includes a polyvinylchloride/polyvinyl acetate copolymer dissolved in a methyl ethyl ketonesolvent.
 8. The method of claim 4 further comprising the stepsof:forming a second elastomeric material by mixing approximately 2.5parts powder component into approximately 1 part liquid component untilall of the powder component is thoroughly moistened; and, applying thesecond elastomeric material to the underlying surface of theoverdenture.
 9. The method of claim 8 further including the stepof:applying a sealer over the exterior surface of the liner to create anon-absorbent exterior surface seal and glaze.
 10. The method of claim 9wherein the sealer includes a polyvinyl chloride/polyvinyl acetatecopolymer dissolved in a methyl ethyl ketone solvent.
 11. The method ofclaim 8 further comprising the steps of:forming a third elastomericmaterial by mixing approximately 3 parts powder component intoapproximately 1 part liquid component until all of the powder componentis thoroughly moistened; and, applying the third elastomeric material tothe underlying surface of the overdenture.
 12. The method of claim 11further including the step of:applying a sealer over the exteriorsurface of the liner to create a non-absorbent exterior surface seal andglaze.
 13. The method of claim 12 wherein the sealer includes apolyvinyl chloride/polyvinyl acetate copolymer dissolved in a methylethyl ketone solvent.